Fluidic catalytic cracker (FCC) reactor technology has evolved over the years, continuously searching to improve yield selectivity of hydrocarbons by minimizing unwanted reactions that occur outside of the FCC riser. Most FCC reactors use a catalyst which is an extremely porous powder that reacts with the hydrocarbon mixture to capture intermetal carbon and metal. In the process, the pre-heated hydrocarbon feed mixed with hot catalyst enters the reactor through one or more risers. The riser creates a fluidized bed where a concurrent upward flow of reactant gases and catalyst particles occurs. Nearly every FCC unit employs some type of separation device connected on the end of the riser which is intended to separate the bulk of the catalyst from the hydrocarbon vapors. The technology includes riser termination devices which range from providing a physical downward deflection of the catalyst as it exits the riser to directly attaching the riser outlet to sets of cyclones. The most commonly used separation devices are vortex separation systems (VSS) and vortex disengager stripper systems (VDS). The vortex separation system includes a tube with a split head located at the riser outlet to separate the mixture. The VDS system has a stripping unit at the bottom of a rough vortex evaporation system and usually forms two stage stripping.
Gases leave the reactor through the cyclones after separation from the powdered catalyst. The gas is then passed to a fractionator for separation into the product streams. The spent catalyst is commonly sent to a regenerator unit and is regenerated by combusting carbon deposits to carbon dioxide. The regenerated catalyst is returned to the reactor for further use. Separation of the gases from the catalyst is seldom totally efficient, whereas gases and catalyst may tend to recirculate in the separation device creating conditions resulting in over cracked gases and over fouling of the catalyst. The present invention provides an improved system for the VSS/VDS technology intended to reduce unwanted catalytic/thermal reactions by minimizing contact of the hydrocarbons and the catalyst outside of the riser.